Ninety minutes changes what the same visit achieves
The work does not get harder when a room is full, it gets smaller. A crew that can reach a quarter of the floor cleans a quarter of the floor, using the same hours and the same equipment. The store pays for an attendance and receives a partial one, and because nobody documented the condition it reads as poor performance rather than as a timing mismatch. That misreading is what damages an otherwise workable arrangement.
Shifting the visit by an hour and a half often resolves it completely, and it costs nothing beyond a conversation. The obstacle is usually habit: the schedule was set when the contract started and nobody has revisited it since the store's delivery day changed. A short annual review of timing against the current delivery pattern is one of the cheapest improvements available in a small retail scope.
